Just got my MkIII Compass back from Trademark London

[bramble]

Atfter having a few power issues my end, Just wanted to add my compass was returned ,certified to within one half of one degree at all four cardinal points. The service included a total clean, all seal replacement and the five tritium lights along with fluid replacment, only this time with purified Kero and other unexpected touches like replacement base rubber and sticker renewal

[trademarklondon]

I received a 1942 TG Co (The Gramophone Company - later became EMI Records) MkIII in poor condition. It had been "repaired" using gunge and surgical spirits that had become liquid glue that coated the inside and outside of the capsule, effectively gluing the capsule into the lower base - a nightmare. This 1942 MkIII also shows that the original MkIII did not have lid window guards. They were brought in later, and where you see an early dated compass with the guards it is because it was an afterfit.

I have taken the unusual decision to re-light this one. I removed all the Radium-226 based old luminous paint and replaced it with Tritium lamps, where I could, and Promethium paint where the lamps won't fit.

You can clearly see the black rubber sealing gasket around the edge of the sealing glass - in the 1940s they used red rubber, which had a much shorter working life, as it was natural rubber.

Attachment 24422

Attachment 24421

[trademarklondon]

Here's a spares diagram for the Stanley (SIRS) G-150 that was free to download from the SIRS website for years, but was removed with a recent site update. It is approximately valid also for the MkIII and the M-73, M-72 and M-71 liquid prismatic compasses.

Attachment 24429

[Claven2]

Great to see you contributing on the forum Paul Hope you keep it up!

The Kodak you rebuilt for me works beautifully. The only down side is the wide band of luminova you applied up under the 360 mark on the rotating glass has turned a brown color - almost radium-like. I'm assuming it's been "burnt brown" by residual radium dust or whatever. Otherwise it remains very nice.

If my G150 "quick fix" of topping with ISO fails, I may have to send this one in for a going over as well.

[trademarklondon]

Hi Ron, sorry that happened, but yes it's caused by residual radiation in the aluminium clamp ring. You could buy a little bottle of luminous paint from a model shop and reapply the light, just scrape out the damaged paint, it's harmless, but don't eat it or, if you do send your G-150 over, put the MkIII in with it and I'll take care of it for you. All my work is guaranteed, even if it's caused by residual radiation :-)

[Claven2]

Hi Paul,

Thanks for the info. I'll try that if it bother me As for the G-150, I topped up the ISO about 6 weeks ago and no bubbles have started to form YET. The original varnish seal over the fibre washer filling screw was all gummy on this compass when I opened it up and the screw was slightly loose, so I'm hoping that proper tightening and properly cured varnish will fix the problem. If not, it means I need a new glass seal for the bowl and it will be off to you for basic maintenance. Thankfully, it's otherwise in very servicable shape and no putty

[trademarklondon]

Hi Ron, the "varnish" on the filler plug screw is a sure sign it has been buggered about with... possibly another QM

Before you top up with Isopropyl alcohol it's best to ensure that what is in there is still Isopropyl alcohol, because if somebody has had a go at it and used meths, turps, or surgical spirits, then putting something different in can cause the two fluids to separate, each having their own specific gravity, which will cause uneven damping, at best, and at worst it could possibly cause other issues.

However, beware of compasses that have varnish on the sealing plug screw... it's a classic QM signature

Hopefully no more bubbles will appear.

[Claven2]

Hi Paul,

Every ex-MOD G150 I have seen (a sample of three - I know, very scientific - most I see regularly are Canadian issue) has a lacquer or varnish over the plug, presumably to mark that it hans't been tampered with? The two compasses I canibalized to make a good one were both written-off MoD compasses, one had a broken case, the other had issues with the bowl. Put good bowl in good case plus swap a few parts = serviceable compass - lol. See the pics furhter up the forum. Both definitely had MoD ISO in them, I didn't use new ISO, I took a little frm one compass to top up the other. As I said, 6 weeks after the work, the G150 still pointing identically to my Kodak MkIII you recently rebuilt for me and no bubble has yet appeared in either the Kodak or the Stanley. If one does turn up, I'll send it in for re-gasketing and a top-up If the G150 leaks, it will likely do so in the first few months I should think. I'm hoping it was just the loose filling plug that was the culprit.

Cheers,
Ron

[trademarklondon]

Great news! The G-150 ex-factory does not have varnish... it simply isn't needed if it is put back together correctly. The G-150 was the leakiest compass probably ever made. Isopropyl alcohol has excellent properties for compass use, but it is so incredibly volatile that it will find a way out... should be called IsoHoudini alcohol That is probably why people have tried many tricks to stop the leakage over the years, but the best one would simply have been to change the fluid and use something equally suitable, but considerably less volatile and aggressive on the seals. Yours may be good for a few more years yet, and even if you have to top it up every six months for the next few years, that's money saved. A service is the last resort, or necessary if you really need to use the compass at night and the lights have failed due to age. Keep topping up, if necessary, and the compass will be fine.
This seems a very friendly forum... it discusses many things outside of my field of competence... I know how to use firearms but I don't collect them or restore them... so I'm fairly limited to helping people with compasses and various other antique scientific or navigational instruments, but if I can help somebody in any way then I'm happy to join in.

[trademarklondon]

I have just moved my website, TRADE MARK LONDON, to a new server, the service offered by the old hosting company was getting worse and worse, and I took the chance to totally re-write the website. There is a lot of new information for compass collectors, including the chance to view the first 320 pages of the book TRADE MARK LONDON in flipbook format on screen, or to download the full high quality version in pdf for printing or viewing on your screen, all 538 pages of it, which I have now basically given to the public domain, and is free to download.

If you collect compasses then the updated site is certainly worth exploring.

Click on my signature link to visit the new site.